It is known to use lightning protection to protect wind turbine rotor blades against damage by a lightning strike. For this purpose, a lightning receptor is usually disposed in the region of the blade tip. The current of lightning striking into the lightning receptor is then diverted, via a lightning conductor, toward the blade root, and from there, via the nacelle and the tower of the wind turbine, into the ground. If a plurality of electrically conductive elements are arranged, more or less in parallel, in the wind turbine rotor blade, electromagnetic induction in the case of a lightning strike causes large potential differences between the electrically conductive elements that can result in flashovers, or even in the destruction of the wind turbine rotor blade. It is known to counteract such flashovers by potential equalization elements.
Such a potential equalization is necessary, in particular, if one of the electrically conductive elements is an electric heating device for de-icing the surface of the wind turbine rotor blade. These heating devices are provided with an electric power supply, and when in operation must be electrically isolated from the lightning protection system. For this purpose, spark gaps may be provided inside the rotor blade, between the heating device and the lightning protection arrangement, as shown in U.S. Pat. No. 6,612,810. In the event of a lightning strike, these spark gaps are bridged, and establish a potential equalization between the heating device and the lightning protection arrangement.
United States patent application publication 2015/0204311 shows a wind turbine rotor blade having an electric heating device and a lightning conductor. The heating device and the lightning conductor are connected to each other, at a plurality of locations over the length of the rotor blade, via spark gaps. The spark gaps are disposed inside the rotor blade, in combination with the lightning receptors.
In order to ensure the operational reliability of the lightning protection arrangement, the functional performance of the spark gaps must be checked regularly. In this case, in particular, spark gaps arranged in the blade tip region are accessible only with difficulty.